Convert a length in bytes to a human readable string with the appropriate unit.

ToHumanReadableString.cs

//we can't shift more than 63 bits with a long, so we would need a big int to support ZB and YB...
static readonly string[] units = new string[] { "B", "KB", "MB", "GB", "TB", "PB", "EB", "ZB" };
/// <summary>
/// Supports any non negative value up to long.MaxValue (~8EB)
/// </summary>
public static string ToHumanReadableString(long length)
{
	if (length < 0) throw new ArgumentOutOfRangeException("length", "length cannot be negative!");
	long shiftResult = 0;
	long previousShiftResult = 0;
	for (int i = 1; i < units.Length; i++)
	{
		shiftResult = 1L << (i * 10);
		if (length < shiftResult || shiftResult == 64) // length < current unit value ? (or overflow, meaning we are in the EB range)
		{
			double value = ((double)length / previousShiftResult); //then we take the previous unit
			string format = value < 1000 ? "{0:#0.0}{1}" : "{0:#0}{1}";
			return string.Format(format, value, units[i - 1]);
		}
		previousShiftResult = shiftResult;
	}
	throw new ArgumentOutOfRangeException("length", "length is too big!"); //This is impossible
}